try to get a rather then a they are much better engines get an oil pump conversion kit since the stovebolts didnt use oil pressure until ish get a half or ton truck anything bigger and youre going to be way over youre head if you are a diehard traditionalist like me you will keep the speed and have a topspeed of mph at k if you want something more practical drop in a t or a r if you change the tranny you have to change the diff since the original diff is a closed driveshaft theres a lot of small stuff about the pre war designs that suck like if youre over six feet your head will hit the headliner i have experience on these trucks so ask away